Flooding of forested valleys by reason of natural causes or by reason of hydroelectric damming may provide a source of submerged free standing trees. A substantial percentage of the submerged free standing trees are within depths of approximately 100 feet of water and so are available to be harvested given an appropriate log cutting and retrieval mechanism.
It is known to provide a vessel, such as a barge, for floating on the surface of the water, with a mounted boom capable of extending under the water surface to cut underwater trees or stumps. A stump cutting apparatus for use underwater is described, for example, in U.S. Pat. No. 5,613,537, issued to Gassiott. U.S. Pat. No. 5,655,584, issued to Clawson describes an amphibious feller-buncher for use in cutting stumps in swampland.
U.S. Pat. No. 6,024,145, issued to Ackles describes an articulated boom mounted to a free floating platform that can be used to manipulate objects under water. This articulating boom is comprised of multiple folding sections that unfold as the wood gripping-cutting head is extended towards the base of a tree to be harvested. The articulating boom requires a large volume of space around the tree so that the arm can unfold without hitting underwater obstructions, and it can not be used effectively in reservoirs with densely packed trees or thick tree canopies.
U.S. Pat. No. 3,667,515 (Corey) and U.S. Pat. No. 4,168,729 (Tausig et al.), teach a pile cutting device for use in locations remote from the operator. A pile cutter is suspended on a cable so that it can be lowered by means of a crane to a desired depth. However, grappling logs with such a system is a very difficult task as there is no rigid connection between the crane and the wood gripping-cutting head. Furthermore, while attachment of the cutting head to a cable is suitable for use in still water, currents may affect positioning the cutting head underwater. In addition, feeding the cutting head through branches of the tree canopy is difficult.
U.S. Pat. No. 3,693,676 issued to Burch, describes an underwater pile cutting saw attached to a rigid tubular housing enclosing a drive shaft. The rigid tubular member (stick) is of a fixed length. Submersed tree harvesting devices with a non sectioned stick are severely constrained regarding the depth they can harvest. If the stick is long, then manipulating and storing the logs at the surface is difficult as the entire length of the stick in addition to the wood needs to be maneuvered.